Technical Field
The present invention relates to a semiconductor module that includes a power semiconductor device and to a method of manufacturing the semiconductor module.
Background Art
Semiconductor modules that include a power semiconductor device exhibit excellent power conversion efficiency and are widely used in renewable energy fields such as solar power generation and wind power generation, automobiles such as hybrid automobiles and electric automobiles, railway applications such as electric trains, and more. In these types of semiconductor modules, a variety of protective measures are employed not only in the semiconductor device but also in the insulating substrate in order to prevent dielectric breakdown even if high voltages are applied.
Patent Document 1, for example, discloses such a semiconductor device in which a protective treatment is applied to the insulating substrate. This semiconductor device includes a power plate on which a semiconductor element is mounted; an insulating substrate on which the power plate is mounted; a filler that covers the surfaces of the semiconductor element, the power plate, and the insulating substrate; and a creeping breakdown prevention member that is arranged only between the edge regions of the power plate and the insulating substrate, that has a higher breakdown voltage than the filler, and that exhibits stronger adhesion with the insulating substrate than the filler.
In Patent Document 1, this creeping breakdown prevention member has a higher relative permittivity than the filler (which is a silicone gel, for example) and alleviates concentration of electric fields at the edges of the power plate. Specific examples of this surface damage prevention member include epoxy resins, epoxy resins in which aluminum oxide powder is mixed, epoxy resins in which aluminum nitride powder is mixed, epoxy resins in which mica powder is mixed, polyester resins, silicone gels in which aluminum oxide powder is mixed, silicone gels in which aluminum nitride powder is mixed, and silicone gels in which mica powder is mixed.